RRC ID 4988
Author Shimizu T, Ohta Y, Noda M.
Title Shiga toxin 2 is specifically released from bacterial cells by two different mechanisms.
Journal Infect Immun
Abstract Shiga toxin 1 (Stx1) is located in the periplasmic fraction, while Stx2 is found in the extracellular fraction, suggesting that enterohemorrhagic Escherichia coli (EHEC) contains a specific Stx2 release system. Both stx(1) and stx(2) are found within the late operons of Stx-encoding phages. Stx2 production is greatly induced by mitomycin C, suggesting that stx(2) can transcribe from the late phage promoter of the Stx2-encoding phage. However, the Stx1 promoter adjacent to stx(1) is a dominant regulatory element in Stx1 production. With the deletion of phage lysis genes of the Stx2-encoding phage, Stx2 remains in the bacterial cells. Further, we demonstrate that the Stx2-encoding phage, but not the Stx1-encoding phage, is spontaneously induced at extremely low rates. These results indicate that spontaneously specific Stx2-encoding phage induction is involved in specific Stx2 release from bacterial cells. Furthermore, to examine whether another system for specific Stx2 release is present in EHEC, we analyze the stx-replaced mutants. As expected, Stx2 derived from the Stx1 promoter is located in both the extracellular and cell-associated fractions, while mutant Stx2 (B subunit, S31N) derived from the Stx1 promoter is found only in the cell-associated fraction. These results indicate that EHEC has another Stx2 release system that strictly recognizes the serine 31 residue of the B subunit. Overall, we present evidence that specific Stx2 release from bacterial cells is involved in both the Stx2-encoding phage induction system and another Stx2 release system.
Volume 77(7)
Pages 2813-23
Published 2009-7-1
DOI 10.1128/IAI.00060-09
PII IAI.00060-09
PMID 19380474
PMC PMC2708558
MeSH Animals Bacteriolysis* Coliphages / growth & development Enterohemorrhagic Escherichia coli / metabolism* Enterohemorrhagic Escherichia coli / virology* Genes, Viral Prophages / growth & development Protein Transport Rabbits Shiga Toxin 2 / metabolism*
IF 3.201
Times Cited 52
Prokaryotes E. coli pFT-A